Compressed-air starting device for internal-combustion engines



May 8, 1928. 1,668,886

H. BECKER couPEEssED AIE STARTING EEvIcE EOE INTERNAL coNEusTIoN ENGINES Filed May 12, 1924 Fiql i C mdf* H d1 WJ Patented May 8, 1928. n

VuNiTEDv STATES PATENT OFFICE.

EINRICH BECKER, iOF KIEL-HASSEE, GERMANY, ASSIGNOR 'IO FRIED. KRUPP AK- TIENGESELLSCHAFT GERMANIAWERFT, OF KIEL-GrAABDEILr GERMANY.

COMPRESSED-AIR STARTING DEVICE FOR INTERNAL-COMBUSTION ENGINES.

Application lcd May 12, 1924, Serial No. 712,880, and in Germany June 2, 1923.

This invention relates to devices for starting internal combustion engines by means of compressed air, and 1t has more particularly reference to devices of this kind in which the n valve gear automatically Aenters into or out of action upon the compressed air being admitted and stopped. v u

ln a known device of this kind shown in U. S. Patent No. 1,413,583, after the passage y outline of the cam. This may be attained in the above mentioned device by making the control piston, which is under the pressure of the compressed starting air, of dimensions so large that it will constantly press the cam roller against the cam disc. But, in such case, the valve would open even if the pressurein the working cylinder were still higher than the pressure of the starting air at the moment the motion of the restraining lever lwaspermitted by the cam, thereby destro-ying the fundamental feature of the above mentioned device.

The present invention has for its object to provide a device which prevents a premature opening of the .starting valve and yet insures a constant contact of the cam roller with the cam disc during the starting operation. y

This object is attained by providing a lost motion connection between the controlling piston and the starting valve and by providing for the application of fluid pressure to the starting valve itself just sufficient to open it when the compression in the cylinder has dropped to the pressure of the starting air, while the pressure on the controlling piston keeps the cam end of the restraining lever in constant contact with the cam, this being permitted whether the starting valve opens or not, because of the above mentioned lost motion connection.

The subject matter of the invention is ilpressed starting air is led through thef'cylinder head to the valve by a conduit a. i In the upper end of the bore ofthe valve casing a controlling piston C is mounted for vertical reciprocation. A small cylinder c is connected to the lower end of niston C by a short neck c2. On the upper end of the valve stein D is mount-ed a piston d* Which reciprocates in the cylinder c. The space above piston Z4 is in communication with the space above the controlling piston C through a bore c3, and both spaces are con nected by means of a pipe M to a source `of compressed air of constant pressure such as the compressed starting air for example. A spring E which is inserted between the valve cage B and the lower face of the cylinder c tends to hold the starting valve closed.

A valve lever H which s mounted for rocking motion on the shaft G has an arm 7L which is forked at its end to embrace the neck c2 of the piston C, While the other arm` of the lever H. carries a roller 71.2 which bears against a cam K, is. The upper and lower surfaces of the forked end of lever arm L are spherical to Vprovide for the relative m0- tion of the piston C and the lever H.

In order to describe the operation of the device it will be assumed that the starting valve should open when the pressure in the working cylinder has sunk below 285 pounds per square inch. The pressure of the starting air is assumed to be 355 pounds per square inch and the Atotal pressure on the starting valve from within the cylinder at 285 pounds per square inch is 2650 pounds, for example. The diameter of the piston d* which is connected with the valve stem is of such a dimension that the greatest pressure of the compressed air transmitted to it is likewise about 2650 pounds. The diameter of the controlling piston C is such that the pressure exerted by the same on the arm 7L of the valve lever through the iniiuence of the compressed air acting on the piston C is about 3300 pounds or more.

Now, when the recess 7c of the cam disc Kfmoves past the cam roller h2 while the pressure in the working cylinder is higher than 285 pounds per square inch, the cam roller h2 will be pressed by the controlling piston C into the recess of the cam disc, but since the pressure on piston Z4 is not great enough to overcome the pressure on the valve d', the valve will remain closed and the cylinder c will simply move downward with relation to the piston (Zt, compressing the spring E. It, on the other hand, the pressure in the working cylinder` is less than Q85 pounds per square inch when the recess 7c moves opposite the roller 7a2, the pressure on the piston Z4 will be sufficient to overcome the pressure on the valve d and the valve will therefore move downward with the piston C and cylinder c. In either case the cam roller 71,2 is constantly held against the cam disc K by the action or the controlling piston C throughout the operation, and therefore the opening of the valve will ltake place without the valve .lever being subjected to any sudden movements or shocks.

pressed air cylinder in which the piston (Z4. .reciprocates, whereby a material simpliiication is attained as will be readily understood.

Having described my invention, I claimt l. In a compressed air starting device :tor

starting Valve, a valve gear adapted to automatically enter into and out of action upon admitting and stopping the compressed air and a controlling piston included in said gear, apressure cylinder and a second piston inserted between the controlling piston and the stem of the starting valve, the diameter of said second piston being of a dimension such as to cause the pressure exerted on it to open the starting valve, independently on the movement oi' said valve gear, upon a determined pressure prevailing in the engine cylinder, and the diameter' oft the controlling piston being of a dimension such as to cause the pressure exerted on it by the compressed starting air to outweigh the pressure ol the said second piston.

2. In a compressed air starting device for internal combustion engines, comprising a starting valve, a Valve gear adapted to automatically enter into and out of action upon admitting and stopping the compressed air and aV controlling pistonincluded in said gear, a pressure cylinder and a second piston inserted between the controlling piston and the stem of the starting valve, the diameter of said second piston being of a dimension such as to cause the pressure exerted on it to open the starting valve, independently on the movement of said valve gear, upon a determined pressure prevailing in the engine cylinder, and the diameter' of the controlling piston being of a dimension such as to cause the pressure exerted on it by the coinpressed startiim` air to outweigh the pressure of the said-second piston, said controlling piston forming at the same time the pressure cylinder for said second piston.

The foregoing speoiication signed at I-Iamburg, Germany, this 23rd day of April,

HEINRICH BECKER. 

